MARKING AN OBJECT

Abstract: A method of marking an object wherein known sheets (2) having a curable print-receiving coating (epoxy and polyamide particles (3)) on one surface and pressure-sensitive adhesive (5) on the other surface (normally used for attaching the printed and cured sheet to a wall or other surface) are wrapped around the object to be marked and the overlapping ends (4) of the sheet are temporarily secured by an overlap bond between the pressure-sensitive adhesive (5) and the curable coating (3). Subsequent curing of the coating fixes the indicia printed thereon and cures the bond to fix the sheet in position. Preferably, the pressure-sensitive adhesive (e.g. acrylic polymer) will interact with the curable coating on curing.

Description: MARKING AN OBJECT This invention provides a method of marking an object, comprising providing a flexible support sheet having, or capable of having, fϊxable indicia applied on one of its main surfaces and having a bond coating of curable material on at least part of one of its main surfaces, wrapping the sheet around the object to be marked so as to bring at least part of the bond coating into contact with another part of the sheet, applying the said indicia, if not already present, and subsequently treating (preferably by heating or U.V. irradiation) to fix the indicia and to cure the bond coating, thereby bonding the sheet to itself in the area of contact. Preferably the sheet is wrapped so as to bring the bond coating into overlap contact with the opposite main surface of the sheet. The bond coating may be on the same main surface of the sheet as the indicia, which may be applied to the sheet by any appropriate method of printing, marking, laminating, transferring or other means. Preferably the indicia are applied to an indicia-receiving coating of curable material carried on one of the main sheet surfaces. The bond coating and the indicia-receiving coating may be of different compositions, but are preferably formed of the same curable material as each other, and are preferably constituted by different areas of a substantially continuous coating of the curable material on one of the main sheet surfaces. The preferred coating(s) is (are) initially porous, preferably being of particulate and/or filamentary curable material. It is preferable that a pressure-sensitive adhesive (preferably acrylic) coating is provided on part of the sheet and is used to hold the bond coating in contact with the other part of the sheet prior to curing. Optionally the pressure-sensitive adhesive is provided on top of the bond coating or on the other part of the sheet which is brought into contact therewith, and preferably the pressure-sensitive adhesive is capable of reacting with the curing bond coating material. When preferred materials are selected, the curing of the bond coating produces a bond of at least 25% (preferably at least 35%, more preferably at least 45% or at least 50%) greater strength (FINAT Test Method No. 1) than the pressure-sensitive adhesive bond prior to the curing. This may particularly be found when a bond coating comprising epoxy material interacts with an acrylic polymer pressure- sensitive adhesive. It may be especially useful if the pressure- sensitive adhesive coating is on the main sheet surface remote from the indicia and also serves to adhere the sheet to the object. The curable material preferably cures on heating by reaction of a plurality of reactive components which exist separately from one another in the form of filaments and/or particles. Preferably a component of the curable material comprises an epoxy material, and preferably another component of the curable material comprises a material having free amine groups. -Alternatively, the curable material may be curable by irradiation, e.g. with UN. light. The indicia may be "fixable" in the sense that suitable treatment, by heatingor U.N. irradiation for example develops their final colour or causes them to adhere more strongly to the sheet. However, the indicia are preferably "fixable" by virtue of curing of the aforementioned indicia-receiving coating to which they are preferably applied. Although this curing may be effected before the sheet is wrapped around the object, or after such wrapping but before curing of the bond coating, it is preferred to cure the indicia-receiving coating in the same heating operation as the bond coating, after wrapping the sheet around the object. In all cases, it is advantageous for the indicia to be fixable by the same treatment as is used to cure the bond coating, preferably in a single operation. The indicia may be applied, or added to, by any suitable methods, for example ink jet printing after wrapping of the sheet around the object, but it will often be more convenient to apply all of the desired indicia before the wrapping step. Any flexible sheet, e.g. a polymer film or laminate of polyester or polyimide, may be used which is capable of receiving' and retaining the coating(s) and indicia, and any suitable curable materials and indicia-forming materials may be used, for example heat-curable epoxy systems or U.N. curable acrylics. Preferred forms of marker for use in the method of this invention are described in EP-A-0237258 (RK297COM), the sheet and coating materials naturally being selected from those described to provide sufficient flexibility for wrapping around the object to be marked. The curable material (at least in the bonding area) is cured after wrapping of the marker around the object, as distinct from the prior curing of the markable surface to make the indelible labels described in EP-A-0237258. The ingenious use of the pressure- sensitive adhesive coating, which may be present on the reverse side of the known labels, to hold the bond contact prior to curing (the pressure-sensitive adhesive preferably reacting with the bond coating on curing), according to the present invention, is an especially advantageous feature of the present invention. Examples of the present invention illustrating different possible arrangements of the components will now be described with reference to the accompanying schematic drawings, showing various forms of marker wrapped around an object (1) such as a pipe, shaft or cable. Briefly, Figures 1 to 4 show constructions having coatings on both main surfaces of the flexible carrier sheet, while Figures 5 to 9 show constructions with coatings on only one surface of the sheet. In the preferred structure of Figure 1, a 50 micrometre thick flexible polyester sheet (2) ("Mylar" Trade Mark) carries on its outer surface a particulate porous curable coating (3) on which indicia (not shown) have been printed as described in EP-A-0237258. An end portion of the coating (3) serves as the bond coating according to the present invention in the area of overlap (4). On the opposite, inner surface of sheet (2) is a coating (5) of pressure-sensitive acrylic adhesive (known per se) which serves both to secure the overlap bond at the ends of the sheet prior to curing and to adhere the sheet to the object (1). After wrapping the sheet, before and /or after applying indicia to the curable coating (3), and establishing the temporary adhesive overlap bond by means of the pressure-sensitive adhesive (5), the assembly is heated to fuse and cure the coating (3). Thus curing fixes the indicia and increases the strength of the overlap bond by reaction of the acrylic adhesive with the curable (epoxy/polyamide) coating (3) in the overlap area (4). Figure 2 shows a structure similar to that of Figure 1 , except that the pressure-sensitive adhesive (PSA) (5) is present on the inner surface of the sheet (1) only in the overlap area (4). Figures 3 and 4 show structures similar to Figures 1 and 2 respectively, except that the curable material coating (3) in the overlap area (4) does not extend over the rest of the indicia-receiving surface. The heat-fixable indicia (not shown) are themselves heat-curable, e.g. being printed using heat-curable ink, instead of relying on a curable receiving coating as in Figures 1 and 2. Figures 5 and 6 show a curable bond coating (3) on the outer surface of sheet (2) in the overlap area (4) only, with a coating of PSA (5) overlying the bond coating (3) in Figure 6, whereas the overlap would have to be held by other means prior to curing in the absence of PSA illustrated in Figure 5. Figure 5 also illustrates the optional use of a separate indicia-receiving coating (6), which may be of different material from the bond coating (3), and need not cover all of the outer surface of sheet (2). Figures 7 and 8 correspond to Figures 5 and 6 respectively, except that the bond coating is carried on the inner sheet surface. Figure 9 illustrates an alternative bond configuration wherein the bond coating (3) and PSA coating (5) are both on the inner surface at opposite edges of sheet (2), and are brought together to form a raised welt joint. Indicia (not shown) could be applied directly to the outer surface of sheet (2), or to an indicia-receiving coating thereon (not shown). Any other practicable novel combinations of the features individually disclosed or illustrated herein may also be used within the scope of the invention. Of course, if transparent or translucent sheets were used, the indicia could be on the inner surface for viewing through the sheet, and this would even be possible with the relatively opaque indicia- receiving coating provided that the indicia were applied in such a way that they penetrated to the interface between the sheet and the coating.

Claims: CLAIMS: 1. A method of marking an object, comprising providing a flexible support sheet having, or capable of having, fixable indicia applied on one of its main surfaces and having a bond coating of curable material on at least part of one of its main surfaces, wrapping the sheet around the object to be marked so as to bring at least part of the bond coating into contact with another part of the sheet, applying the said indicia, if not already present, and subsequently treating to fix the indicia and to cure the bond coating, thereby bonding the sheet to itself in the area of contact. 2. A method according to claim 1, wherein the sheet is wrapped so as to bring the bond coating into overlap contact with the opposite main surface of the sheet. 3. A method according to claim 1 or 2, wherein the bond coating is on the same main surface of the sheet as the indicia. 4. A method according to any preceding claim, wherein the indicia are applied to an indicia-receiving coating of curable material carried on one of the main sheet surfaces. 5. A method according to claim 4, wherein the bond coating and the indicia-receiving coating are formed of the same curable material as each other. 6. A method according to claim 5, wherein the bond coating and the indicia-receiving coating are constituted by different areas of a substantially continuous coating of the curable material on one of the main sheet surfaces. 7. A method according to any preceding claim, wherein the coating(s) is (are) initially porous, preferably being of particulate and/or filamentary curable material. 8. A method according to any preceding claim, wherein a pressure- sensitive adhesive (preferably acrylic) coating is provided on part of the sheet and is used to hold the bond coating in contact with the other part of the sheet prior to curing. 9. A method according to claim 8, wherein the pressure-sensitive adhesive is provided on top of the bond coating or on the other part of the sheet which is brought into contact therewith, and preferably the pressure-sensitive adhesive is capable of reacting with the curing bond coating material. 10. A method according to claim 8 or 9, wherein the curing of the bond coating produces a bond of at least 25% (preferably at least 35%, more preferably at least 45% or at least 50%) greater strength than the pressure-sensitive adhesive bond prior to the curing. 11. A method according to any preceding claim, wherein the curable material cures by reaction of a plurality of reactive components which exist separately from one another in the form of filaments and/or particles. 12. A method according to any preceding claim, wherein a component of the curable material comprises an epoxy material. 13. A method according to any preceding claim, wherein a component of the curable material comprises a material having free amine groups. 14. A method according to claim 8, 9 or 10, wherein the pressure- sensitive adhesive coating is on the main sheet surface remote from the indicia and also serves to adhere the sheet to the object. 15. A method according to any preceding claim, wherein the fixing of the indicia is effected by the same treatment as the curing of the bond coating, preferably in a single operation. 16. A method according to any preceding claim, wherein the fixing and/or the curing is (are) effected by heating or by irradiation.

Inventors: HILL GERALD CHRISTOPHER PAUL, HILL, GERALD, CHRISTOPHER, PAUL
Applicants: HILL GERALD CHRISTOPHER PAUL, RAYCHEM LTD, HILL, GERALD, CHRISTOPHER, PAUL, RAYCHEM LIMITED
Application year: 1994
Main classification: G09F3
IPC codes: B29C35, B29C65, G09F3